Formation of authigenic minerals associated with microbial activity in ferruginous sediments, Lake Towuti

• Applicant: Dr. Aurèle Vuillemin
• Subject Area: Palaeontology ; Hydrogeology, Hydrology, Limnology, Urban Water Management, Water Chemistry, Integrated Water Resources Management ; Microbial Ecology and Applied Microbiology
• Term: from 2015 to 2021
• Project identifier: Deutsche Forschungsgemeinschaft (DFG) - Project number 270921149

Authigenic minerals in lacustrine settings can be formed in the water column and within sediments, abiotically and/or triggered by biological activity. In order to use authigenic minerals as proxies for lacustrine environments, one needs to define carefully the settings to which they refer, whether associated with specific sedimentary inputs, water column processes or microbial activity within the sediment. Lake Towuti, Indonesia, is a tropical 200-m deep tectonic basin seated in ultramafic rocks and surrounded by areas with lateritic soils. As a result, its sediments are very rich in iron and other metals, providing microbial communities with a wide range of metalliferous substrates. These elements further influence primary productivity along with the development of specific microbial metabolic pathways involved in biogeochemical cycling and early diagenesis. The ICDP Towuti Drilling Project scheduled in May/June 2015, which will include a core entirely dedicated to geomicrobiological investigations, will provide the opportunity to identify authigenic minerals and diagenetic processes associated with sedimentary microbes. The main goals of the project are to trace microbial diagenesis within metal-rich subsurface sedimentary environments, define indicators of microbial mediation in iron mineralization and establish the phylogenetic distribution of microorganisms involved in the biogeochemical cycling of iron. For this, a combination of genetic fingerprinting techniques and advanced geochemical analyses by electron microscopy will be applied. Firstly, our analyses will detect sedimentary horizons in which microbes have overprinted the preexisting mineralogy. Secondly, phylogenetic data will reveal the relationship between microbial species and sediment mineralogy as well as mutualistic interactions in the coupling of biogeochemical cycles. Thirdly, it will shed light on authigenic minerals that can be unequivocally used as biosignatures in the context of ancient iron formations and life on the early Earth. Together, the present research project should bring new understanding on microbe/mineral interactions and on the use of authigenic minerals as relevant indicators of biogeochemical processes in lakes.

• DFG Programme: Infrastructure Priority Programmes
• Subproject of: SPP 1006: International Continental Scientific Drilling Program (ICDP)
• International Connection: Canada
• Cooperation Partners: Professor Dr. Sean Crowe; Dr. Jens Kallmeyer